What is light?

Light is “made” of Electromagnetic Waves.
You can call them “EM Waves” for short.
There are a lot of Electromagnetic Waves that we cannot see with our eyes. Radio waves are EM waves, X-rays are EM waves. What we call “light” are the EM waves that our eyes can “see”. We have little cells in our eyes that can absorb a small range of the EM waves and transmit signals to our brain. That is how we see.

If you think about ocean waves, you have waves that are spread out and you have waves that are close together. It’s basically the same for electromagnetic waves. Our eyes are tuned, sort of like tuning a radio to pick up your favorite station, to pick up a small set of the EM waves that are all around us!
We can make other tools to “see” radio waves and x-rays and turn them into waves that we can see with our eyes but, our eyes are not turned to see them on their own.